Rare diseases Xagena

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Ocular findings in ochronosis: therapeutic options include protein restriction, administration of high dose Vitamin-C or Nitisonone

Ochronosis / Alkaptonuria is a tyrosine metabolism disorder where accumulation of homogentisic acid, in eye, skin, cartilage and several other connective tissues leads to a black pigmentation of the affected tissues. It is autosomal-recessive inherited in men with a frequency of 1-9/1,000,000.

While it is clear that pigment deposits lead to joint destruction, renal stone formation and cardiac valvulopathy respectively, the significance of ocular findings is still unclear.
Researchers have evaluated the frequency and clinical significance of ocular findings in ochronosis and discuss possible therapeutic options.

The search revealed 36 case reports including 40 patients. Average age at the onset of ocular signs was 40.6 years.

The most frequent sign was symmetric brown sclera pigmentation present in 82.5% of the patients.

Oil-drops, brown pigment spots in the limbus are generally considered pathognomonic but were a little less frequent ( 75% ).

Vermiform pigment deposits at the level of the conjunctiva or increased conjunctival vessel diameter is also frequent.

Researchers found an increased incidence of central vein occlusion and elevated intraocular pressure going along with chamber angle hyperpigmentation.

Another condition observed twice is rapid progressive astigmatism attributable to corneoscleral pigment accumulation.

In conclusion, the observations suggest that ocular findings are of double relevance. First, characteristic ocular findings can anticipate the time of diagnosis and second, ocular findings may complicate to various conditions putting sight at risk.
Therapeutic options include protein restriction, administration of high dose Vitamin-C or Nitisonone. ( Xagena )

Lindner M, Bertelmann T, BMC Ophthalmol. 2014;14:12. doi: 10.1186/1471-2415-14-12.